1. Field of the Invention
The invention relates to a display data-generating device, a method of generating display data, a display apparatus, and a system comprising a display data-generating device and a display apparatus.
2. Description of the Related Art
International Patent Application WO-A-99/21355 discloses a system of a computer and a monitor for improving the image quality of selected video windows when the video information in the window is a photograph or moving video. This document states possible image quality improvements for this kind of video information: increased sharpness or contrast, gamma or color correction. However, if these image quality improvements are performed on characters and numerals, the readability will decrease. It is, therefore, required to generate information in the computer to provide the monitor with the position of the window, only inside which the image quality improvement has to be performed.
In an embodiment, the position information comprises a first pulse signal which corresponds to the width in the horizontal direction of the window, and a second pulse signal which corresponds to the width in the vertical direction of the window. It is mentioned that this approach has the drawback that a separate wire connection is required between the computer and the monitor. Therefore, in the other embodiments disclosed, marker signals are generated in the video information which is transported from the computer to the monitor to indicate the start and the end position of the window. It is a drawback that these marker signals are permanently visible for every window.
It is, inter alia, an object of the invention to generate information indicating a position of a window, this information being less visible.
To this end, a first aspect of the invention provides a display data-generating device for generating window position indicating data. A second aspect of the invention provides a method of generating display data indicating a position of a window. A third aspect of the invention provides a display apparatus for use with such a display data generating device. A fourth aspect of the invention provides a system comprising such a display data-generating device and such a display apparatus.
The display data-generating device (for example, a computer), in accordance with a first aspect of the invention, generates display data (also referred to as video information) to be displayed on a display device (for example, a computer monitor). The display data-generating device further generates coordinates determining a window of the display data. One of these coordinates may indicate, for example, the starting pixel number in a line where the window starts. The display data-generating device further generates reference information indicating a time of occurrence and a corresponding running number of a first predetermined pixel, and a time of occurrence and a corresponding running number of a second predetermined pixel of the display data. It is possible to determine, from this reference information, the instant of occurrence of a pixel for every given running number of this pixel (for example, the starting pixel number of the window). This has the advantage that the reference information needs to be available only once, while the instants of occurrence of several windows are determined from the coordinates of the windows and this single reference information. This will become clear, in more detail, after elucidation of the operation of the display apparatus in accordance with the third aspect of the invention. The display data, the coordinates, and the reference information are provided at an interface which may be, for example, a standard VGA connector.
The display apparatus, in accordance with the third aspect of the invention, comprises a picture enhancement circuit which, under the control of a control signal generated by a control circuit, enhances the picture quality of video information displayed within a window. The control circuit receives the reference information and the coordinates determining the window. The relation between the running number of a pixel and its instant of occurrence can be determined from the reference information. For example, the distance in time between two consecutive pixels can be determined from the time of occurrence and a corresponding running number of a first predetermined pixel, and the time of occurrence and a corresponding running number of a second predetermined pixel. Consequently, it is possible to.determine the instant of occurrence of the start of an arbitrary window from the running pixel number indicating the start of this window by multiplying the difference in running numbers between one of the predetermined pixels and the window start pixel with the distance in time between two consecutive pixels.
The invention is applicable to the horizontal position of pixels in a line of a field of the display data, or to a vertical position of lines in the field. If transposed scanning is applied, whereby lines which are written in the vertical direction succeed each other in the horizontal direction, the words vertical and horizontal in the previous sentence should be exchanged.
It is important to translate the running numbers of pixels into instants of occurrence because there is no one-to-one link between the timing of the video data pixels supplied by the display data-generating device and the instant of occurrence (which determines the position on the display screen) of these pixels in the display device. For example, in the line direction, the active line period is defined as the period of time from the first pixel in a line up to the last pixel in the line. The total line period is the sum of this active line period during which the video information is displayed and a blanking period during which no video information is displayed. The total line period is also referred to by its reciprocal: the line frequency. In a display apparatus with a cathode ray tube, a major part of the blanking period is used for the flyback of the horizontal deflection from the end of the active video period (the end position of the visible video, usually near the right edge of the picture tube screen) to the start of the active video period (the start position of the visible video, usually near the left edge of the picture tube screen) of the next line. In current computer monitors, it is required to be able to display several graphical resolutions which give rise to several different line frequencies. As the minimal flyback time is limited, the ratio between the active line period and the blanking period differs for different line frequencies, and, therefore, it is not known when the first active video sample exactly occurs with respect to the horizontal synchronization pulse which is the only horizontal position information supplied by the computer and available in the monitor. Consequently, the extra reference information is required to determine the instant of occurrence of the window from the window coordinates.
The window coordinates may comprise a first running number indicating the horizontal start position of the window, a second running number indicating the vertical start position of the window, a third running number indicating the horizontal end position of the window, and a fourth running number indicating the vertical end position of the window. It is also possible to provide running numbers indicating the horizontal and vertical start positions and further information indicating a period of time between the respective start and end positions.
In one embodiment of the invention describing a preferred solution, the first predetermined pixel is the start pixel of the active line period, and the second predetermined pixel is the last pixel of the active line period. Now, the reference information only needs to comprise the time of occurrence of these first and last pixels, and the total number of pixels in a line period.
In another embodiment of the invention, the reference timing information, which indicates the time of occurrence of the first and the second predetermined pixel, is encoded in the display data. This has the advantage that this information is transported between the computer and the monitor via a standard interface without the need for an extra wire.
In another embodiment of the invention, the reference timing information is an analog signal having a level change at the instants of occurrence of both the first and the second predetermined pixel. For example, a first pulse is generated with a rising edge at the instants of occurrence of the first predetermined pixel, and a second pulse is generated with a rising edge at the instants of occurrence of the second predetermined pixel. Or, alternatively, all pixels of a line have a high level. The reference information may be encoded in one or more of the red, green, and blue data signal.
In another embodiment of the invention, the reference timing information is encoded in one line of a field. In this way, the visibility of the reference timing information is minimized. In a preferred embodiment, this line is the last line of a field.
In another embodiment of the invention, a software driver of the graphics adapter instructs the operating system (for example, Windows 98(copyright)) that the resolution format of the display data supplied by the graphics adapter has a predetermined number of lines which is smaller than are actually available. These reserved lines are used to transport the reference information or the reference timing information. The predetermined number depends on how many lines are required to transport the information. In this way, the transported information will not be disturbed by the operating system or application software running under the operating system, because the reserved lines are not available for both the operating system and the application software.
In another embodiment of the invention, the window coordinates are transported from computer to monitor via a digital bus.
In another embodiment of the invention, the running numbers indicating the first and the second predetermined pixel or the total number of pixels in a line period are transported via the digital bus.
In another embodiment of the invention, the coordinates of the window and the running numbers indicating the first and the second predetermined pixel or the total number of pixels in a line period are encoded in at least one of the data signals.
In another embodiment of the invention, the visibility of the reference timing signal is further minimized by displaying the reference timing signal only during a very short time required by the monitor to extract the information for use. The reference timing signal is only required during start-up of the display apparatus or after a change of the graphic resolution of the video data supplied by the display data-generating device.
In another embodiment of the invention, a detector determines whether the nature of the video content in a window is of such a kind that video enhancement will improve the performance. The window(s) coordinates information is only sent to the monitor if at least one window is present with a nature of the video content for which an improvement is possible. In this manner, the window(s) coordinates information is only sent to the monitor when required and the visibility of this information is further minimized.
In another embodiment of the invention, an indication of the nature of the video content in a window is sent to the monitor to enable the monitor to perform a picture enhancement processing optimally fitting this nature.
In another embodiment of the invention, a very simple relation determines the relation between the instants of occurrence of the start instant of a window and the instants of occurrence of the first and last pixel in the active line period and the total number of pixels in an active line period.
In another embodiment of the invention, the enhanced display signals are blanked during the video lines which comprise the reference information or the reference timing information. In this way, the lines comprising this information will not be visible to the user.
In another embodiment of the invention, the peaking properties of the peaking performed on the data in the window are dependent on the line frequency to obtain an optimal performance improvement.
In another embodiment of the invention, the white color temperature of the data in the window is adapted in accordance with a desired white color as determined from the video properties and provided by the computer, or as desired and inputted by the user.
In another embodiment of the invention, the contrast and/or brightness of the data in the window is adapted in accordance with a desired setting as determined from the video properties and provided by the computer, or as desired and inputted by the user.
In another embodiment of the invention, the gamma of the data in the window is adapted in accordance with a desired gamma as determined from the video properties and provided by the computer, or as desired and inputted by the user.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.